Making a centrally controlled navbar

I know there is a way of doing this, but I don't remember how and can't seem to find an answer.
I know you can control the way it's set up through the CSS sheet. But, I want to control the content, add an item or take one away without having to edit every page on the site.
What kind of sheet do I use to do that?

I've never done anything with php before, or any other server side language. I think I may have done this with JavaScript before, but it was long ago and far away. And a lot of what I used to think I knew, I need to re-learn.

I understand how you feel. If you really like code, then you should have no problem learning everything you can about it. I'm always learning new techniques and languages. Trust me, PHP include/require statements are some of the easiest functions to implement. Simply put the code for your navigation in a file called "navigation.php" and then include it in your index.php wherever you want it to appear.